Nine patients with malignancy requiring chemotherapy were evaluated before, during, and in the recovery phase of their antineoplastic regimen with selected absorptive studies and jejunal biopsies. Depression of the crypt mitoses occurred without change in the indices of absorption. The mitotic indices returned to pretreatment counts on the recovery phase biopsies. Even after prolonged therapy, restudy in three of the patients failed to demonstrate clinical mal-absorption. We conclude that chemotherapy-related mal-absorption does not contribute to overall malnutrition of cancer patients during the first months of treatment.